1. Field of the Invention
The present invention relates to a fuel supply device for an engine, the fuel supply device including a fuel tank and a fuel pump for supplying fuel in the fuel tank to a carburetor of the engine.
2. Description of the Related Art
In some small outboard motors, for example, a fuel tank is disposed in a top cowling in which an engine is housed. In this structure, the fuel tank is positioned such that a fuel level in the fuel tank is higher than a fuel level in a float chamber in a carburetor so that fuel is supplied from the fuel tank to the carburetor using the head difference between the fuel levels.
Alternatively, a fuel pump can be disposed in the middle of a fuel supply conduit so that fuel can be supplied to the engine immediately and constantly even when the fuel levels have no head difference therebetween (see JP-B-2717272, for example).
However, when the fuel pump is disposed in the middle of the fuel supply conduit in a conventional fuel supply device, the fuel pump impedes the flow of the fuel through the conduit during an off period of the fuel pump, thereby obstructing fuel supply to the carburetor even when the head difference between the fuel levels is at a certain distance. Starting the engine for a first time or after a long interval takes a large amount of time because the carburetor contains no fuel therein. Particularly when the engine is started with a recoil starter, this can cause a user to incorrectly believe that the engine has failed.
Increasing the head difference between the fuel levels is expected to be effective in assuring that fuel is supplied to the carburetor before the fuel pump starts driving. However, due to restrictions such as the space necessary for providing the fuel tank, there is a limit on the distance by which the head difference can be increased.